Machine for removing hardened paint



Dec. 29, 1959 H. c. SUNDSTROM MACHINE FOR REMOVING HARDENED mm Filed Sept. 14, 1956 United States Patent MACHINE FOR REMOVING HARDENED PAINT Harold C. Sundstrom, Chicago, Ill.

Application September 14, 1956, Serial No. 609,887

Claims. (Cl. 15-4) This invention relates to a portable machine for removing hardened paint.

The removal of paint from the exterior of a house, or the like, in preparation for repainting the same has generally been a disagreeable task involving considerable labor. Traditionally, such hardened paint has been removed by heating small areas of the paint with the flame of a blow torch to soften the paint and then manually scraping off the softened paint with a putty knife or other appropriate bladed tool. Although this method effectively removes the paint, it is obvious that considerable labor must be expended to accomplish the scraping, and the method may not be employed without some danger due to the use of an open flame.

A number of methods and devices have been proposed heretofore foralleviating these problems, including devices that combine in a single unit an electric heater arranged to heat the hardened paint and an ordinary blade adjacent the heater to scrape the heated paint from the surface as the unit is manually forced thereacross. Although much of the danger of fire is eliminated by these devices, the amount of labor involved in effecting the removal of the paint remains practically the same as with the blow torch method and, apparently, none of these devices have proven entirely satisfactory for one finds that the trade in general still resorts to the tried and true blo-w torch-scraper method. Another device that has been suggested for the removal of hardened paint is a rotary chipper which uses power driven rotary cutter heads to literally cut the paint from the painted surface. Although the cutter heads are adjustable so that the depth of cut may be controlled within limits, it is evident that such cutting action cannot occur without the danger of also cutting away a measurable amount of the surface underlying the paint.

'It is the primary object of this invention to provide a novel paint removing machine that requires little effort to operate and which will speedily remove hardened paint from a surface such as the exterior of a house or the like.

Another object of the invention is to provide a novel paint removing machine that may be utilized to remove hardened paint from wood surfaces, or the like, without danger of igniting the surface and without danger of unduly removing the surface beneath the paint.

Still another object of the invention is to provide a ma chine for removing hardened paint that first softens and thereafter removes paint by abrasion as the machine is guided across a painted surface.

Other objects and advantages of the invention will become apparent from the following description taken in conjunction with the accompanying drawing wherein:

Fig. 1 is a pictorial view of one embodiment of the invention as it would appear in the hands of an operator using it to remove hardened paint from the surface of a wall or the like;

Fig. 2 is a plan view of the bottom or underside of the device illustrated in Fig. l;

Patented Dec. 29, 1959 Fig. 3 is a longitudinal sectional view of the device as seen along line 3--3 in Fig. 2;

Fig. 4 is a sectional view of the device as seen along lines 44 in Fig. 3; and

Fig. 5 is a sectional view of the device as seen along line 55 of Fig. 3.

In general, the objects of the invention are accomplished by providing a portable machine having heater means for softening hardened paint and a motor driven rotary brush positioned adjacent the heater means so that it abrades and brushes away the softened paint. Although the machine must be guided across the painted surface by an operator, none of the operators effort must be expended to effect the actual removal of the paint, and the paint may be removed without interruption as fast as the heater is capable of softening the paint sufficiently for its removal by the wire brush.

Referring to the drawing, a preferred embodiment of the invention is shown in Fig. 1 as it would appear when being operated by a workman to remove the paint from a painted wall surface. Actual removal of the paint is accomplished by the unit, shown generally at 11, held in the operators right hand. In this instance, the unit 11 is powered by a portable electric motor 12 which is carried in a sling 13 over the operators shoulder and is connected to an electric outlet by an extension cord or the like (not shown). The motor 12 is operatively connected to the unit 11 by a flexible shaft 14. This arrangement reduces the weight that must be supported by the hand of the operator and, inasmuch as the unit 11 is independent of the weight of the motor, a larger motor may be used to power the unit then could be tolerated if the motor were mounted directly on the unit 11.

As shown in Figs. 2 to 5, the paint removing unit 11 comprises generally an elongated housing 16 including a handle 17 extending lengthwise of the housing, a plurality of heater elements 18 carried by the housing 16, and a rotary brush 19 also carried by the housing 16. The housing 16, in this instance, is a sheet metal enclosure having at one end thereof an elongated generally rectangular portion 21 that serves to cover the heater elements 18 and an inwardly curved or recessed portion 22 at the other end that serves to contain the brush 19. The inward curvature of the portion 22 carries it around to form one end 23 of the housing, while the end of portion 21 opposite portion 22 is bent around to form the opposite end 24 of the housing. The longitudinal sides of the housing 16 between ends 23 and 24 are closed by a pair of sheet metal pieces 26 shaped to conform to the general longitudinal profile of the housing and the underside of the housing is substantially open. The handle 17 is secured to the top of the housing 16 by appropriate fasteners, such as a rivet 25 and a screw 31, and extends longitudinally along and above the top of the housing 16.

Although there are a number of types of heaters that will adequately serve to soften paint, in this instance heaters 18 are shown as electric resistance heaters arranged in side-by-side recessed relation in the housing 16 so as to expose a maximum heating surface to the painted area. Each of the heaters 18 comprises a plurality of longitudinally extending resistor elements 27 embedded in a block of heat-conducting ceramic material 28. The ceramic material 28 evenly distributes the heat generated by the resistor elements 27 and radiates that heat to the painted surface, and in addition, also serves to protect the enclosed resistor elements 27 against inadvertent damage that might occur during that receives the ends of the heaters 18 and an upwardly and laterally extending flange portion that is secured to the elongated housing portion 21 by the screw 31 which in this instance, also serves to secure the forward end of the handle 17 to the housing portion 21. The Opposite ends of heaters 18 are supported by an angle member 32 that extends transversely across the housing 16 .and which has its ends bent upwardly and secured to the side pieces 26 by screws 33 (Fig. 4). The member 29 and the angle 32 are arranged and dimensioned sothat the heater elements 18 are spaced slightly away from any surface over which the machine may be moved. Thus, the heaters 18 do not normally contact the painted surface, but are retained in slightly spaced relation therefrom during use of the device.

To prevent the handle 17 and those parts of the machine adjacent thereto from becoming too hot for convenient handling, a sheet of thermal insulating material ,34 is disposed within the housing 16 between the upper surface of the heaters 18 and the elongated housing portion 21. The insulation 34 is held in position in the housing portion 21 by a pair of transversely extending clamping members 36 and 37. The member 36 has a flange portion 33 engaging the insulation 34 and an oppositely extending flange portion 39 engaged by the screw 31. The member 37 has a flange portion 4-J hearing against the insulation 34 and a depending rear flange 41 extending between the housing and the heaters to seal off the elongated hollow interior of the housing portion 2 1 from the curved recess defined by the portion 22 of housing 16.

.For abrading and removing the paint softened by the heater elements 18, the brush 19 is rotatably mounted immediately adjacent the heaters within the recess provided by the inwardly curved housing portion 22. In this instance, brush 19 is an elongated cylindrical wire brush and has a mandrel or shaft 42 that is journaled in appropriate bearings in the side pieces 26 so that the brush extends transversely across the housing. The ends of the shaft 39 extend outwardly beyond the sides 26 of the housing and are provided with flat portions 43 (Fi 2) adapted to make a detachable driving connection with the flexible shaft 14. As seen in Figs. 3 and 5, brush 19 is mounted in the housing 16 so that a portion of its periphery extends beyond the housing through the open underside to contact and abrade, during operation, any surface along which the machine is guided. The brush 19 is shown in this instance as extending substantially the full width of the heater elements 18 so that the entire width of the surface heated and softened will thereby be abraded and removed.

For conveniently controlling current flow to the heaters 18, an electric switch 44 (Fig. 3) is mounted on the housing 16 beneath the handle 17. Switch 44 is carried by a bracket 45 fastened to the housing portions 21 and 22 by screws 46 and is electrically connected in the heater circuit, the heaters likewise being connected to a source through a conductor cable or cord shown fragmentarily at 47.

In operating the machine, it has been found that excellent results are obtained when the painted surface being removed is maintained at as high a temperature as is consistent with good safety practices and when the wire brush is rotated at very high speeds. Furthermore, it is preferred that the brush 19 be rotated in a counterclockwise direction (as viewed in Fig. 3) so that the particles of paint removed thereby will be directed and discharged away from the heating elements 18. Stray particlcs of paint that might cling to the brush are prevented by the rear flange portion 41 of the clamping member 37 from entering the space within the housing above the heaters 18. Although a plurality of brushes can be used, it has been found that if suflicient rotative speed and power are provided the single brush arrangement shown does an excellent job. Furthermore, al-

though it is feasible to change the axis of rotation of the brush so that it is other than transversely across the width of the housing, the arrangement shown is capable of best performance in many specific instances, such as removing paint from Weather boarded structures or the like.

It is thus seen that this invention provides a novel machine for removing hardened paint from a surface such as Wood or the like. The machine is portable and swiftly removes paint from such a painted surface. Moreover the machine requires little effort on the part of the operator who is obliged only to hold the machine and guide it across the painted surface. Moreover, by having a separate motor unit With a flexible drive connection to the brush it is possible to provide all of the required power for any use of the device without imparting excessive weight to the heater-brush unit so that the latter can be manipulated with ease.

Although the invention has been described in connection with a certain specific structural embodiment, it is to be understood that various modifications and alternative structures may be resorted to without departing from the scope of the invention as defined in the appended claims.

I claim:

1. A portable machine for removing hardened paint, comprising an elongated housing having a closed top and closed sides and having an open underside, a handle on said top, heater means mounted in said housing adjacent one end thereof for heating an area of paint through said open underside, and a generally cylindrical wire brush rotatably journalled transversely in said housing at the opposite end thereof with a peripheral portion of the brush projecting from said housing through said open underside adjacent said heater means for contacting and abrading the heated area during rotation of said brush as said machine is moved longitudinally across a painted surface, said brush being rotatable in a direction to move said projecting peripheral portion away from said heater means.

2. The machine of claim 1 further characterized in that said wire brush is sufficiently long to extend substantially the full width of the heated area.

3. A machine according to claim 1 and further charac terized in that heater means comprises at least one resistance heating element mounted in a heat conducting enclosure having a surface exposed through and extending across said open underside to uniformly heat by radia tion the area of hardened paint.

4. A portable machine for removing hardened paint comprising an elongated housing having a heater compartment at one end thereof and an inwardly curved brush compartment at the other end thereof, a handle secured to said housing and extending lengthwise thereof for manipulating the machine as a unit, enclosed electric heater means mounted in said heater compartment, a transverse shaft journallcd in said inwardly curved brush compartment, a rotary brush mounted on said shaft in said brush compartment and disposed adjacent said heater means, at least one end or" said shaft projecting from said housing and having means providing a detachable connection with a flexible shaft of a portable power source, and partition means in said housing separating said compartments whereby paint particles rcmoved'by said brush are prevented from entering said heater compartment, said heater means being slightly recessed within said heater compartment so that when the machine is positioned in operative relation against a painted surface the heater means is spaced slightly from said surface for heating the same primarily by radiation, said brush having a peripheral portion projecting from said housing whereby to make direct contact with the painted surface for abrading the same following the heating thereof by said heater means, said brush being rotatable in a direction to move means.

5. The machine of claim 4 further characterized in that said heater means comprises a resistance heating element embedded in a heat radiating ceramic block, the outer surface of said block being recessed slightly within said housing so as to avoid direct contact thereof with the painted surface during use of the machine.

References Cited in the file of this patent UNITED STATES PATENTS 1,011,490 Rasmesen Dec. 12, 1911 6 MacLaurin Sept. 5, 1916 Multhaup Apr. 3, 1928 Hollnagel Sept. 3, 1929 Fingerhart et a1. Apr. 16, 1935 Blakeslee Jan. 12, 1943 King Mar. 30, 1943 Sickles Jan. 30, 1951 FOREIGN PATENTS Germany Oct. 3, 1929 

